study guide two

Question 1

below is a life table for fictitious population of turtles in the arboretum on the UCD campus. which statement is best supported by the life table?

a. this population has a type I survivorship curve
b. the age class with the highest mortality also has the highest fecundity
c. on average, each female will have 5.3 offspring throughout her life
d. fecundity increases throughout the entire life of the individual
e. none of the above are supported by this life table

Answer 1

e. none of the above are supported by this life table

Question 2

each graph below depicts population growth over time for different populations, shown by dotted, dashed, or solid curves. answer the following questions using these two graphs
a. which of the graphs (left or right) describes exponential growth?

b. on the left graph, which population has the highest r?

c. on the right graph which population has the highest K?

d. on the right graph, which population has the highest r?

Answer 2

a. left
b. dashed line
c. dashed line
d. solid line

Question 3

in population of birds, we find that as the number of birds increases, the birth rate is decreasing and the death rate is increasing. this population is likely…

a. experiencing exponential growth
b. density independent
c. at rick of extinction
d. approaching its carrying capacity
e. maintaining a stable population size

Answer 3

d. approaching its carrying capacity

Question 4

below are data for a fictitious population of ducks at the arboretum on the UCD campus. use the data to answer the following questions.

a. calculate the following for this populations: R0, G, r

b. is this population increasing or decreasing? how do you know?

Answer 4

a. R0: 8 , G: 5.75, r: 0.36

b. increasing; the R0 value is greater than 1 and the value is grater than 0, both of which indicate a population that is increasing

Question 5

assume the population below experiencing exponential growth. the exponential growth equation is Nt=N0e^r(t)

a. for a population of 275 individuals with r= 0.3, what will the population size be after 3 years?

b. for a population of 500 individuals with r= 0.04, what will the population size be after 3 years?

c. for a population of 275 individuals with r= 0.3, how many years will it take for the population to double in size?

d. how long will it take for a population with r=0.04 to double in size?

Answer 5

a. 676.39
b. 564.75
c. 2.31 yrs
d. 17.33 yrs

Question 6

given the following patterns of birth (solid line) and death (dashed line) rates in a population over time, sketch a graph of population size through time (hint; you can start at any non-zero population size)

Answer 6

Question 7

assume the populations below are experiencing logistic growth. round your answers to the nearest whole organism. the logistic growth equation is

a. for a population of 800 individuals with r= 0.15, living in an environment that can support 1000 individuals, what will the population size be after 1 generation?

b. for a population of 200 individuals with r= 0.15, living in an environment that can support 1000 individuals, what will the population size be after 1 generation?

c. which of the population from parts A and B above have a large increase in population size in a single generation? explain why that population has a larger increase than the other population

d. is it possible biologically for a population to ‘overshoot’ the carrying capacity and have a larger population size than the environment can actually support? if so what will happen to this population?

Answer 7

a. 823
b. 225
c. population B has a larger increase in population size in a single generation, because 25/200 > 23/800; but both are experiencing slow growth.
d. yes it is possible; the population will likely face a negative growth rate until it falls below K

Question 8

explain the difference between r and R0. under which values of each is population growth positive, negative, and zero?

Answer 8

R0: the average number of offspring an individual is expected to have over its lifetime

r: growth rate of population

a. R0 > 1 & positive r: population is increasing as individuals replace themselves

b. R0 < 1 & negative r: population is decreasing as not all individuals replace themselves

c. R0 = 1 & r = 0: population is stable as individuals are just replacing themselves

-variation in reproductive output can be high, so a R0 greater than1 can occur even if some individuals have no offspring

Question 9

how can scientists estimate population size (N0) of naturally occurring organisms? how can we estimate per capita growth rates (r)?

Answer 9

initial population (N0): estimated through direct counting or mark-recapture studies (including photographic mark-recapture)

growth rate(r): estimated by tracking a population over time or using life table analysis to derive r from R0

Question 10

you are studying a population of feral cats which currently number 437 individuals while the carrying capacity is approximately 500 cats for this region. the population is causing problems by hunting native birds and lizards and so your management goal is to get the population of cats down to 200 cats in the next 10 years.

a. what r value would you need to achieve in order to hit this target?

b. how many offspring, on average, can cats in this population have throughout their lifetime in order to stay below that r value? assume generation time in cats is about 1 year

Answer 10

a. -0.234
b. R0: 0.7914